Preoperative medical consultation associated with increased mortality and hospital stay

In an effort to keep people who undergo major surgery safe, surgeons frequently refer their patients for evaluation by internal medicine specialists before the planned surgery. This evaluation is called a “preoperative medical consultation.”

Many people who undergo major surgery have pre-existing medical problems, such as important heart or lung disease. These medical diseases account for many deaths and major complications after surgery. The preoperative medical consultation allows the internist to optimize a patient’s medical conditions, arrange for specialized tests to determine a patient’s risk for surgery, start medications with the aim of reducing the risk of complications after surgery, and arrange for closer follow-up of a patient after surgery.

But new research from the Institute for Clinical Evaluative Sciences (ICES), St. Michael’s Hospital and the University Health Network shows that although these consultations are associated with increases in preoperative pharmacological interventions and testing, they are also associated with a small increase in mortality and hospital stay after major elective non-cardiac surgery.

The study of almost 270,000 people who had major elective surgery in Ontario between 1994 and 2004 found:

• 39 per cent had undergone preoperative medical consultation.
• Patients who had undergone consultation were more likely to undergo specialized heart and lung tests before surgery.
• These patients were also more likely to be started on medications called beta blockers. During the time period of the study, medical guidelines recommended beta blockers as a therapy that would reduce the risk of heart attacks after surgery. However, more recently, large trials suggest that routine preoperative beta blocker usage may cause more harm than benefit.
• Patients who had undergone consultation did not have a reduced risk of major complications after surgery. Indeed, they had a slightly higher risk of dying at 30-days after surgery. This risk was 1 extra death for every 516 people who had undergone consultation.

“We don't know why there was this small increase in death, because internists do have special expertise that undoubtedly helps patients. However, they may also be doing things that harm patients. One possibility is the use of beta blockers, the other is the investigation and treatment of low risk patients in whom the risks of investigation and treatment may outweigh the benefits. It is very important that we improve our knowledge about which components of pre-operative consultations work and which don't, and that internists follow evidence-based guidelines as they are developed,” says Dr. Duminda Wijeysundera, lead researcher on the study.

The study found several areas that should be improved so that medical consultation will provide greater benefits to Ontario patients:

• Some of the tests ordered by internists did not provide useful information for improving patients’ care.
• More studies are needed to find medications that can safely reduce patients’ risks of medical complications after surgery. For example, beta blockers were recommended during the time period of the study, based on a few relatively small studies. However, more recent and better quality studies have shown that beta blockers may instead be harmful to patients undergoing surgery. Thus, while internists were following recommendations from guidelines, those guidelines were based on weak evidence that turned out to be incorrect.

Author affiliations: ICES (D. N. Wijeysundera, P. C. Austin, J. E. Hux, A. Laupacis); Keenan Research Centre, Li Ka Shing Knowledge Institute of St Michael’s Hospital (D. N. Wijeysundera, A. Laupacis); Dept. of Anesthesia, Toronto General Hospital and U of T (D. N. Wijeysundera, W. S. Beattie); Dept. of Health Policy Management and Evaluation, U of T (D. N. Wijeysundera, P. C. Austin, J. E. Hux, A. Laupacis); Dept. of Medicine, Sunnybrook Health Sciences Centre and U of T (J. E. Hux); Dept of Medicine, St Michael’s Hospital and U of T (A. Laupacis).

The study “Outcomes and processes of care related to preoperative medical consultation,” is in the August 9, 2010 issue of Archives of Internal Medicine.

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.

FOR FURTHER INFORMATION, PLEASE CONTACT:

• Deborah Creatura
• Media Advisor, ICES
• [email protected]
• 416-480-4780 or cell 647-406-5996